Alcohol and the Law for Drivers Under 21 Years

If you are under 21 years of age, as little as one sip of alcohol makes it illegal for you to drive. If you are convicted of driving after consuming alcohol and your BAC is at any measurable amount, you can be fined and your license will be suspended or revoked. Consult your state's Drivers Handbook for details.

Most states (e.g., California, Connecticut, Delaware, Florida, Michigan, New York, Texas) have Zero Tolerance Law for minors. In Utah there is a "Not a Drop" Act which is same as Zero Tolerance.
ZERO TOLERANCE means that if the minor has ANY detectable amount of alcohol in his or her system while operating a vehicle in a public place, the minor driver has committed the criminal offense of DUI and his or her drivers license is suspended and the officer can take the license immediately.